Telephone-exchange.



0. A. ANDERSON. TELEPHONE EXCHANGE.

APPLICATION FILED JAN. 3, 1905.

PATENTED MAR. 5, 1907.

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No.846,381. PATENTED MAR. 5,1907.

' 0. A. ANDERSON.

TELEPHONE EXCHANGE.

APPLICATION FILED JAN. 3; 1905. t

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APPLICATION FILED JAN. 3, 1905.

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' UNITED STATES PATENT OFFICE.

CLARENCE A. ANDERSON, OF SALINA, KANSAS, ASSIGNOR OF ONE-HALF TO JOHN ANDERSON, OF SALINA, KANSAS.

TELEPHONE-EXCHANGE.

Specification of Letters Patent.

Patented. March 5, 1907'.

Application filed January 3, 1905. Serial No. 239,344.

To all whom it may concern.-

Be it known that I, CLARENCE A. ANDER- soN, a citizen of the United States of America, and a resident of Salina, county of Saline, and State of Kansas, have invented certain new and useful Improvements in Telephone-EX- changes, of which the following is a specification.

My invention relates to party-line telephone-exchanges, and has lor its object improvement in the arrangement and operation of such exchanges.

In the accompanying drawings, Figure 1 is an elevation of the switching mechanism used at each local station and also in a modified form at the central office. Fig. 2 is a section on the line 2 2 of Fig. 1. Fig. 3 is a detail. Fig. 4 is a diagram of the mechanism and circuits at the central oflice, and Fig. 5 is a diagram of two local stations.

In the said drawings, Ais a magnet adapted to move its polarized armature A in either of two directions, according to the direction of the current flowing through it. On the armature A is an arm A which carries a pawl A ad apted to engage the teeth of the segment of a ratchet-wheel C.

Pivoted at a convenient place is aholdingpawlD, providedwith a pinD, projecting adjacent to the rear of the driving-pawl A When a current flows in the operating direction through the magnet A, the impulses advance the wheel C step lay step. When an impulse flows in the opposite direction, the pawl A rides up over the stationary pin A, so as to clear the ratchet-wheel C. It also strikes the pin D, thus lifting the holdingpawl D and permitting the ratchet-wheel C to return to its normal position under the action of the spring C.

There is a projection C on the wheel C, which is adapted to engage a spring 62 at one point in its forward movement. This point is a different distance fromthe normal posi tion in the switching mechanisms of the different stations.

There is a magnet B whose armature B is adapted to close spring to spring 59 when attracted. Pivoted at a convenient place is a catch-lever E, operated hya spring E. When the armature B is attracted, the lever E catches under a pin B and holds the armature in its attracted position, with springs 59 and 60 in connection with each other. The upper end of the lever E, as shown by dotted tion No.

lines in Fig. 1, projects adjacent to the arm A so that when the said arm is moved to release the wheel C it also strikes the catchlever E and releases it from the pin B. When this occurs, the armature B drops by gravity to its normal position, permitting springs 59 and 60 to separate.

In arranging an exchange I provide a central office from which may run any numlter of party-lines, each line of which may have any desired number of local stations. For each local station I provide a switching mechanism like that described, and also at the central office, as a terminal of each line, a similar switching mechanism slightly modified in its electrical connections. Also at each local station are a receiver R, a hook H, an induction-coil K, an alternating-generator G, a ringer Q, a key, and electrical connections, as shown. At the central office are similar receiver, induction-coil, and generator. There is also a drop-magnet F, whose arma ture F carries a piece of insulation F arranged to spread the adjacent springs when the drop is actuated. A main battery X has its ground connections broken by this action of the drop F. A second battery Y serves to supply current for the drop F, as will lce hereinafter explained. Also at the central office are two keys N and N, which may he moved in either direction to actuate the adjacent springs, as will l:ecome apparent in descri ing the operation. These springs are connected, as shown, to plugs. Bridged ltetween the lines for one of these plugs is a clearing-out drop J. There is a jack for each'line entering the central ofiice.

At the normal position of the ratchet-wheel G at the central office the projection C engages a spring and holds it from the adjacent contact-point 91. At the first move ment of the switching mechanism at the central office this connection is closed and completes the circuit for the drop F. This circuit remains closed until the switch returns to its normal position. The operation of magnet B at central also closes the circuit for the drop upon its first operation and maintains the closure until its armature is released as a result of releasing the switch. As a result of this the circuit for the drop F may he closed in either of two ways.

Assuming that the suhseriher at station No. 1 wishes to talk to the sulcscriher at sta- 2, the operation will be as follows:

The subscriber at station No. 1 presses key 16 either before or after removing his receiver B when a current flows: X, 10, 11, 12, 13, ground to station No. 1, 14, B, 15, 16,17, 18, back to central oflice, 19, B, 20,21, 22,23, This actuates the magnets B of both the central oflice and station N o. 1. At the central office the armature B closes connection to contact-point 25, when a current flows: Y, 24, 25, B, 26, 27, F, 28, Y. This operates the drop and calls the operator at the central oflice. The operation of the drop causes the insulation F to spread the springs 12 and 21, thus breaking the connection to the battery X and preventing any other subscriber op erating his magnet B by pressing his key 16. At station No. 1 the magnet B closes connection between springs 59 and 60, which connection is part of the talking-circuit for that station. Upon receiving a signal the operator inserts one of the plugs, preferably plug L when both stations are on the same line, in the jack M. She also presses key N to the left. Beginning at the receiver of station No.1 the talking-circuit is R, 29, 30, 16, 17,18, to central 31, 32, 37, 33, 39, 40, K, R, 41, 42, 65, 54, 55,56, to station No.1, 57, 53, 59, 60, 61, 63, H, K, 64, R. The calling subscriber notifies the operator that he wishes to talk to station N o. 2. The operator then presses key N toward the left when a current flows: X, 66, 67, 68, 36, 37,32, 31,18,17of all stations on the line 30, A, 57, 56, 55, 54, 65, 43, 69, 70, 71, 23 X. This operates the switching mechanisms of all stations one step forward. As it is station N o. 2 that is wanted, the operator repeats the movement of key N, so as to send two impulses over the line. If it had been station No. 10 that was wanted, she would have sent ten impulses, so as to bring the projection C of that station in connection with its spring 62. As but two impulses were sent, it is station N o. 2 that has this connection made. Station No. 1 has been moved past this connection and the other stations have not yet reached it. She then presses key N toward the right and turns her generator-crank, when a current flows: G, ground to station No.2, 14, 72, 73,74, Q, 75, H, 63, 62, o 57, 56, 55, 54, 65, 43, 44, 45, 76, 77, G. This calls station N 0. 2, whereupon the subscriber there removes his receiver. Beginning at station N o. 1 the talking-circui t is: R, 29, 30, 16,17,18, 17 ofstationNo.2, 16, 30,29, R, 64, K H, 63, 62, C 57, 56, back to station No.1,57, 58,59,60,61,63,H,K, 64,11. Itwill be observed that this circuit passes through 59 and 60 at the calling-station and through 62 and C at the called station. This is true in any case, because the calling subscriber in calling operates his connecting-magnet B, and the operator in selecting a desired station connects C to 62. N hen through talking, the subscriber hangs up his receiver and turns his generator-crank. Current flows: G,

; J, 53, 52, 51, 50, 49, 43, 47, 46, 44, 43, 65, 54, 55, 56, 57 of the calling station, 58, 59, 60,61, 63, H, 75, Q, 74, G. Upon receiving this signal through the clearing-out drop J the operator moves key N toward the right, when a current flows: X, 66, 80, 84, 43, 65, 54, 55, 56, 57 of each station, A, 30,16,17,18, 31, 32, 37, 36, 81, 82, 23, X. A branch of this also goes through A of the central ofiice. This is a current in the opposite direction through the magnets A and causes them to release their switching mech anisms. This rel ease permits all p arts to return to their normal positions. At the central office the return of B and (l to their drop-magnet F, which circuit was closed during the entire time between the call being turned into central and the release. Breaking the circuit through F permits F 2 to rise, so that springs 12 and 21 may again close to the springs 11 and 22. It also permits the operator to close the shutter of the drop, a thing which she cannot do until the line is released. In case the original call from station N o. 1 is for a station on some other line the plug L may be inserted in the jack for the calling-line and the for the called line. For the plug L in the jack M the talking-circuit is: R of calling station, 29, 30, 16, 17, 13, 31, 32, 33,34,35,36, 37, 38, 39, 40, K, It,-41,42, 43,44, 45, 46, 47, 48, 49 50,51, 52, 53, 54,55, 56,57, 58,59,60,61, 63, H, K, 64 R. Upon the subscriber learning what station is wanted on some other line she inserts plug L in the ack for that line and then proceeds to call the desired station on that line the same as described before calling a station on the calling-line.

It will be observed that the operatingmagnets A are bridged between the branches of the talking-circuit. They are, however, of high resistancesay about two thousand four hundred ohms. The cutting-in magnets B are operated two in series, the one at the calling-station and the one at the central oflice. They are of less resistancesay about eighty ohms. The drop-magnets 1* are operated by small local batteries and are preferably about two ohms resistance.

In exchanges of this kind to preserve pri-- vacy of conversation it is necessary that the operation of selecting a station by the central oflice be uninfluenced by any operations. performed by the subscribers at their star. tions. A good way, if not the best way, to accomplish this end is to use a magnet for connecting the station telephonicall r to the.- linc. In this case the magnet B is used for this purpose at the calling-station, the called station being connected by a contact-maker engaging a contact-point. At the central ofiice the magnet B is used as a relay for the c rop b. i

It will be seen from the description that normal positions breaks the circuit of the a plug L in the jack this is a lock-out systemthat is, a system in which it is not possible for other persons than the calling and called subscribers to listen to conversation. The calling subscriber by pressing'key 16 gets possession of the line as against every one else except the operator at the central office. In reality this system is a combination between a sys tem which connects stations by moving the contact-makers to desired connections and a system which uses a connecting-magnet for completing the talking-circuit. There are several advantages in this system which do not exist in either of the other systems by themselves. When a subscriber on one line wants to talk to some one on another line, the operator does not have to call back on the calling-line to connect the calling sub-- scriber. This savesa material part of the time required in making connectlons when the system is strictly of the look-out character. In other lock-out systems it is usual for the operator to make one contact for each station on the line and one extra contact for each desired station. To do this expeditiously requires the use of a special calling device. In the present case no second contact is needed, and consequently it is not necessary to have a special calling device. When a line is not busy, a subscriber gets lock-out connection and calls the central office by the mere pressing of a button, or the same thing might be done by the mere rising of the receiver-hook. In the present case the drop which is operated in calling the central office is energized by a local battery and cannot be restored until the line is released. This indicates when a line is busy and avoids the frequent trouble of the operator restoring the drop and forgetting to re lease the line.

What I claim is- 1. The combination with a central oflice, a party-line, a battery, and a series of local stations, of a magnet at each stationfor connecting it telephonically to the line, a signaling device at the central office, means by which a subscriber at any other station may send a signal to the central office, means by which the sending of such a signal will operate the connecting-magnet of the station from which such signal is sent, and means by which the operation of the signaling device at the central office will break the connections to said battery so as to prevent any other station from having its connecting-magnet similarly operated.

2. The combination with a central office, and a series of local stations connected to a partyline, of a switching mechanism at'each station, a similar switching mechanism and a signaling device at the central office, means by which an operation of a local-station switching mechanism causes a similar operation of the central-office switching mechanism, and means by which the central-office switching mechanism serves as a relay for said signaling device.

3. The combination with a central office, a series of local stations, a party-line, and a main battery, of a drop and a local battery therefor at the central office, a magnet at each local station by the operation of one of which its stations are telephonically connected to the line, means by which upon a subscriber closing the connection between his magnet and the main battery he will also cause the connection to be closed between the drop and the local battery so as to cause its operation, and means by which an operation of the drop opens the main-battery connection so as to prevent a similar closure by a subscriber at some other station.

4. In a party-line exchange, the combination with a battery by means of which the party-line is operated so as to establish telephonic connections between stations, of a linedrop for indicating calls on the line, and means by which an operation of said drop will disconnect said battery from the line.

5. The combination with a central office, a party-line, and a series of local stations each provided with an ordinary telephone set, of a contact-closing device at each station adapted to be operated by a subscriber thereat, a station-connecting magnet at each station and a signal-controlling magnet at the central office, a battery having connections extending to said magnets, means by which upon a subscriber operating his contact-closing device he will cause an operation of his own magnet and the signaling device at the central ofiice, and means by which an operation of the signaling device breaks the battery connections to said magnets.

6. The combination with the central office and the local stations of a party-line exchange, of a drop and local battery therefor, means by which a signal sent over the line connects said drop to said battery, means by which the operator at the central office may restore the line to its normal position after a signal has been sent over it, and means by which the connection between the drop and the battery will notbe broken until the line is so restored.

7. In a party-line exchange, the combination with a source of electricity by means of which the party-line is operated so as to establish communicating connections between stations, of a signaling device for indicating calls on the line, and means by which an operation of said signaling device will disconnect said source of electricity from the line.

, Signed at Salina, Kansas, this 24th day of December; 1904;

CLARENCE A. ANDERSON. Witnesses:

FRANK It. SPIER, FRED. H. QUINCY.

IIS 

